DSA (Digital Subtraction Angiography) is known as one of imaging methods for blood vessels in an X-ray diagnostic apparatus. DSA is the technology to generate subtraction image data between frames of X-ray image data before and after injecting a contrast agent into an object, for diagnosis. That is, X-ray image data are acquired before injecting a contrast agent as a mask image data for generating subtraction image data. On the other hand, X-ray contrast image data is acquired by injecting the contrast agent. Then, DSA image data is generated for diagnosis by subtraction processing between the X-ray contrast image data and the mask image data.
Such DSA image data can be generated as image data in which unnecessary anatomies in observation of a blood vessel are removed. That is, diagnostic image data in which blood vessels enhanced by a contrast agent are depicted selectively can be obtained. Consequently, images useful for diagnosis of a blood vessel can be displayed.